Note updating the images is awkward in wikibooks so 2.65 instructions have been simply added.

We start with the default screen in Blender. For 2.65 click on view menu lower left corner then select right.

We want to be able to adjust the size easily and exactly so we need the properties on screen. Press the "N" key to show this. 2.65 has a super set of properties. Also note in 2.65 you may need to go to view and select view persp/ortho to select the ortho view.

Our basic house is going to be 18 feet wide, 30 feet deep and 18 feet high. It's simpler to work in meters with Blender so go to Google and type in "18 feet in meters to feet" the answer is 5.48, 30 feet is 9.144 so we type these numbers into the dim property tag. Z is height, y is width, and X is depth. For 2.65 these go into the dimensions:

Blender centers the object at 0,0,0 we want our house to be at ground level. So we divide the Z value (height) by two and put that number into the Z location field.

To make the roof we will first duplicate the house, so <shift D> followed by <escape>. Now we need to raise the roof by the height of the house so add in 5.48 to the existing Z value to give 8.22.

Roofs are usually pointed so we need to edit our cube. We press "A" to deselect everything.

Next we switch into edit mode from object mode at the green arrow. Then we select the top corners by pressing B then drawing a box round the top corners. We merge them together by scaling the y axis to zero, "S","Y","0" <enter>. Now we eliminate duplicate vertices by pressing "W" then "remove doubles" from the menu. For 2.65 you may need to repeat this for the rear two vertices.

To adjust the shape go back to object mode and adjust the numbers in the properties tag to make the roof a little wider than the house giving it eaves by increasing the Y value and a little lower in height by reducing the Z value. We can also change the name of the cube to roof too make it a bit easier for us to keep track.